The Finder is the heart of your Mac. It provides access to files and folders, displays windows, and generally controls how you interact with your Mac.
There are a few methods for opening windows in the Finder to let you get at your files.
On your Dock, click on the Finder icon (looks like a smiling face).
Click on your desktop (don't select an app or program), click on File in the Menu bar and choose New Finder Window.
On your keyboard, hit 'Command-N' while you have the desktop selected. The Sidebar is the section on the left of the Finder window. You can customize this to display what folders and hard drives you see for easy access.
While in Finder, click on the Menu Bar and select Preferences.
Then select Sidebar.
Check the boxes next to the items you want to see in your Finder's Sidebar.
You can even drag an existing folder into the Sidebar to create a shortcut.